1. Field of the Invention
The invention relates to radiocommunications systems providing the link between subscribers, possibly mobile, and one or more fixed central stations over frequency jump channels and more particularly to a system of this type in which the information is transmitted in a redundant way over the successive steps of the frequency jump law characterizing the link.
2. Description of the Prior Art
In a system where the links are provided over frequency jump channels, a frequency jump law may be assigned to each mobile unit. The laws of the different mobile units of the same space-time-frequency continuum are independent but change values simultaneously and the values of the frequencies are chosen from the same predetermined set of frequencies. Transmission takes place over frequency bursts separated from each other by dead times which facilitate the frequency changes.
In such a system, there exists intrinsic interference resulting from the simultaneous transmission on the same frequency by two transmitters of the network, when the frequency jump laws corresponding to these two links overlap on a given burst; the associated receiver may then detect, if no additional precautions are taken and if the level of the interference is greater than the level of the communication in progress, data transmitted by a transmitter which is not associated therewith.
It is therefore necessary in such a system to provide means ensuring continuity of transmission so that the data detected correspond to the same communication, the data received which do not correspond to the communication in progress being suppressed.
This suppression must be made by whole bursts since the intrinsic interference extends over whole bursts, all the bursts being transmitted in synchronism in the system.